In recent years, solid-state image sensors such as charge coupled devices (CCDs) or complementary metal oxide semiconductor (CMOS) image sensors have been widely applied to electronic products for converting light into electrical signals. The applications of image sensor components include monitors, cell phones, scanners, digital cameras, and so on. Currently, these applications tend to have an overall size which is smaller and thinner so that it can be carried around easily.
Conventionally, these sensors have been packaged for use by mounting them to a substrate and enclosing them within a housing assembly. For example, U.S. Pat. No. 6,268,231 discloses a CCD package 10 as shown in FIG. 1. The CCD package 10 includes a plastic base structure 12 for support beneath a flexible circuit board 18. Electrical conductors are formed upon flexible circuit board 18. Plastic ring frame 14 is placed on top of the flexible circuit board 18 creating a sandwich area defined by the base structure 12 and plastic ring frame 14 with flexible circuit 18 in between. The plastic ring frame 14 provides depth for an image sensor to be contained therein. The image sensor electrical connectors that make electrical contact with conductor pattern on the flexible circuit 18. The ring frame 14 provides support for a glass cover 16 that provides isolation from ambient conditions for the enclosed CCD while allowing light to pass and become incident upon the CCD. The plastic base structure 12, circuit board 18 and ring frame 14, not to mention the glass cover 16, overall forms a relatively thick package.
Similarly, U.S. Pat. Nos. 6,034,429, 6,268,654 and 6,143,588 also disclose a CCD package including an IC die mounted on and wire bonded to a first side of a BT substrate, a bead or dam formed in varying manners around the IC die, a glass lid attached to the bead, and solder balls attached to a second side of the BT substrate. All of these packages are relatively thick and are limited by the thickness of the substrate.
Therefore, a packaging method of an image sensing device having a reduced size and thickness is desperately desired so as to fit within those aforementioned smaller and thinner applications.